Wednesday, July 25, 2012

The heavy rains that have been inundating the
city of Mumbai
and it surrounding regions time and again during the monsoons every year
indicate that the city is still short of a sound flood mitigation framework.
The existing efforts by the city’s governing and planning authorities towards
formulating flood alleviation strategies have only been marginally successful
in fulfilling their purpose. Moreover, the national disaster management
framework released in the year 2004 takes a holistic approach at managing and
reducing disasters by suggesting general policies applicable to all the states
in the country and not just the Mumbai region in particular. The framework also
considers floods only as one of the many natural disasters that it suggests
strategies for. It does not provide any flood-specific mitigation strategies so
to speak of.

The Chitale Committee appointed by the
governing authorities of Mumbai, following the floods of 2005, does provide
some mitigation strategies specific to flooding. However, these strategies have
succeeded only partially in tackling the flooding in the following year. Thus,
this study aims at suggesting improvements to the existing flood-mitigation
framework of the city to minimize or if possible, completely avoid the
destruction of life and property and the disruption of the normal functioning
of the city which results from the floods. For this purpose, this study conducts
case-studies of other flood stricken areas and refers other professional
literature as a guideline to suggest additional flood mitigation strategies
specific to the city and the region of Mumbai. The flood mitigation framework
can be broadly classified into pre-event measures and post-disaster measures. In
an approximate chronological order these are as follows:

3. Role of Government and Private Sector in the flood mitigation framework

1.Pre-flood measures:

As is generally believed, prevention is
always better than cure. Investing time, finance and efforts in the conceiving
the pre-event flood mitigation strategies may considerably save efforts needed
for post-event flood mitigation strategies. They may also reduce the
destruction of life and property to a large extent.

1.1.Limiting the floods and their
after-effects:

Floods are a
form of natural disaster that cannot be totally avoided. However, their
intensity and their after effects can be considerably reduced by adopting the
following actions.

1.1.1.Data Collection and Analysis

Under this plan of action, climatic
data stating expected amount of rainfall is collected with the help of
satellite images and this information is integrated into the geographic data
demarcating the flood prone areas, using GIS.

This data will then be used by the planning
authorities to reserve open spaces in the floodplains such as flood basins or
wetlands for the water to accumulate in the event of floods and prevent urbanization
of these areas by way of land-use and zoning regulations. Figure 1 shows a map
with suggested zoning strategies of the flood prone areas of Mumbai to mitigate
the effects of flood. The areas shaded in green are coastal zones, highly
susceptible to inundation from high tides as well as heavy rains. They should
thus be zoned as open recreational spaces that can act accumulation points for
rain and flood waters. Residential, commercial and any kind of development that
might have habitable spaces should be prohibited in these areas, as a part of
this zoning. The development in the areas shaded in brown should be also be
guided by building codes that reduce the vulnerability of the building
occupants to the adverse effects of flooding as discussed in the following
section.

1.1.2.Vulnerability
Reduction

Figure 2: Building designs suggested as mandatory flood

mitigation strategies in flood prone

areas of Mumbai.

·The building codes should include flood
mitigation measures such as mandatory flood control devices, use of specific
impervious building materials, specific building methodology to create
water-tight enclosures and elevation of the habitable floors of a building
above the expected level of flood. Figure 2 shows graphical representation of
elevation levels of buildings suggested for flood prone areas of Mumbai. The
blue portion depicts the mean flood level and the yellow portion shows the
level of habitable spaces in the building. Such elevation should be mandated in
flood prone areas demarcated in brown and green (if any) in the Figure 1. Other
flood mitigation strategies that can be mandated in flood prone zones of Mumbai
include designing buildings to regulate rain water for constructive use such as
watering planters. Figure 3 shows how an impervious
material covers the exterior of the building and is laid at a grade at its
junction at ground level, such that the rain water flows down and is directed
to the surrounding planters.

Figure 3: Flood-proofing in building design

that can also
be used to redirect storm water to irrigate plantations.

·The building codes should mandate alternative
power supply such as generators as a standby in the event of the failure of the
city’s main power lines.

The data generated by GIS can also be used to restore
the natural eco-systems by way of reinstating the region’s natural flora and
fauna. The reclaimed land around the Bandra Kurla complex along the bank of the
MithiRiver has been extensively concretized
and has also reduced natural course of the river. However the opposite bank of MithiRiver
is occupied by slums and has been considered by the government for slum redevelopment
program. Considering the inundation of
Mumbai during the years 2005 and 2006, the bank should be reserved as open
space, with exposed natural soil that can serve as a seepage ground for flood
water and can also restore natural ecosystems. This scheme would be an
extension of the MahimNaturePark
that has been developed towards this cause.

Figure 4: Map showing reclaimed land on the Banks of MithiRiver
that should be reserved as an Ecological reserve

Figure 5: Map showing recommended

locations for
installation of levees. (In Black)

Figure 4 shows a map depicting the
reclaimed land on the banks of MithiRiver that can be
restored as ecological reserve. This strategy will also solve the issue of
subsidence, a phenomenon that usually occurs on reclaimed lands. Zoning the
reclaimed lands as open recreational spaces will eliminate the vulnerability of
future developments to subsidence.

·Flood control devices that should be installed
at particular locations in the flood prone areas are levees. These levees have
to be constructed with strong, impermeable materials. Figure 5 shows specific
areas in Mumbai wherein installation of levees can significantly reduce their
susceptibility to floods. Areas such as the Thane Creek, the Mahim Creek and
South-Eastern Coast of Mumbai are probable locations which need levees.

·To facilitate the zoning of flood prone
areas as open spaces and water reservoirs the government can exercise
land-acquisition, compensatory regulations and transfer of development rights. Land acquisition gives the local governing authorities the right to
acquire flood prone areas and have full control over their development in the
pre- and post disaster period. Such acquisitions mainly depend on state
funding.

On the other hand
compensatory regulations and transfer of development rights are special forms
of land-acquisition which compensate land owners in exchange for the restrictions
of use on their land. By practicing these rights the government can restrict
development of floodplains and compensate the land-owners in these floodplains
for the losses incurred from the loss or transfer of development rights.

·Maintenance of existing drainage and proper
design of new drains can considerably reduce the extent of flooding in Mumbai.
Some of the actions that can be taken to achieve this task are:

-Design closed
drains which prevent them from collecting silt and garbage.

-Regularly clear
the drains off the accumulated silt and sewage to facilitate the free flow of
water, using modern day equipments. Scrap the water table.

·Relevant departments should be established by
the state government to handle specific disasters such as floods.

·Each department of the State Government should
set apart an appropriate portion of funds under the plan for specific projects
addressing vulnerability reduction and preparedness in the event of floods.

·There should be a close interaction between the
corporate sector, nongovernmental organizations and the media in the city wide
efforts for flood prevention and vulnerability reduction.

·Lastly, one of the most effective pre-flood
mitigation measures is to allow citizen participation and input in planning flood
mitigation strategies to come up with the best possible solutions. Different
strata of society, especially in Mumbai, show varied perceptions and
relationships to natural hazards, and reflect different socio-economic and
socio-psychological backgrounds. Thus, involving the general public in disaster
mitigation decision-making processes may enable local authorities to develop
hazard mitigation strategies that gel well with the local context and thus address
the concerns and social expectations of different population subgroups.

1.1.Preparation for Floods

As mentioned earlier, floods may not
be totally avoidable. However there are certain strategies that can be applied
to prepare the flood prone areas to deal with the floods when they occur and
prevent loss of life and property. Some of the strategies under this category
are as follows:

1.1.1.Prediction

The meteorological department of Mumbai
should use modern technology that can accurately forecast weather. Programs
like GIS can be used to process satellite images to predict the weather
changes. This can be relayed to the masses through a range media including
television, newspapers, radio and internet.

1.1.2.Emergency
Preparedness

Emergency preparedness
for floods broadly includes strategies such as monitoring and alerts;

·The process of gauging rainfall should be
carried out using automatic rain gauges as opposed to the manually operated
rain gauges currently used by the city. These rain gauges can be calibrated to relay
alarm at predefined values of rainfall intensity. The data from the rain gauges
will ultimately serve as warnings in case a possibility of flooding is
detected.

Figure 6: Sensors in the installed in the levees

to relay
warnings at critical pressures

·The levees should be
armed with elaborate fiber-optic sensors (Figure 6) that detect the forces
within the structure, so as to provide a prior warning of the critical
pressures that could cause its damage or collapse.

·Buildings such as local schools, in flood prone
areas, which can be used as shelters for flood victims, should be essentially
designed to provide with sufficient sanitation and other facilities to house
the flood victims.

·In areas,
surrounding the flood-prone zones, flash floods are likely. These areas could
be guarded from floods by use of in-place flood control devices such as water
tight gates. Water tight enclosures should be mandated as a building code in
all the future developments in the city.

·Above all, there should be a well developed
communication between all the departments of the government responsible for
flood mitigation and water management.

· Civic amenities like
pipelines carrying sewage and water should be planned away from each other and constructed with flood resistant materials, to prevent contamination of clean
water and the spread of epidemics.

·The roads should be constructed out of
flood-resistant materials that can withstand the wear and tear caused by heavy
rains during the monsoons.

·Restoration of slums should be avoided at all
cost, especially along the banks of the city’s drainage outfalls, such as the MithiRiver.
Alternatively, the population of settlements along the banks of MithiRiver
should be relocated under the city’s Slum Redevelopment scheme to a safer
location. This would prevent clogging the banks of the river and considerably
reduce the extent of flooding of the area and its precincts.

1.1.3.Education,
training and awareness

·Creating awareness amongst the masses about the
floods and their mitigation strategies helps prevent panic and chaos.

· Awareness should also be created to help harvest the excess rain water and use it for appropriate purposes

·Citizens should be trained to operate the in-place
flood control devices installed in the buildings they occupy. This would help
protect themselves and their belongings, without much delay in the event of
floods.

·The government should mandate periodic safety
drills to help citizens remain alert for any catastrophe and also to ensure
proper functioning of the flood-mitigation equipments.

2.Role of the Government and the Private Sector in the flood mitigation
framework:

2.1. Role of
the Government

For
pre-flood as well as post mitigation strategies, the Government should serve as
a one point contact coordinating between various city agencies such as the weather
bureau, the telephone department, other media such as radio and television, electricity
department, civic amenities department, port authorities and roads department, as
these departments as consortium are responsible for the normal functioning of
the city.

The
Government should also formulate policy guidelines and institutionalize a suitable
co-ordination mechanism between the various agencies including the ones
mentioned above along with the city police department and rescue operations
team that are concerned with the disaster management in real time.

In fact,
each level of government has a different role to play in the flood vulnerability
reduction. Thus, it is essential that these roles be performed as a part of a
coordinated strategy. Overlapping the functions and responsibilities many
needlessly exhaust the resources and waste valuable time, thus weakening the
resilience to the floods. In putting up an effective strategy against floods,
each level of the government should have a definite understanding of its role
and specific responsibilities within the overall structure of the flood
mitigation framework. For this purpose, adequate resources need to be made
available and key responsibilities of the government in this regard include:

Defining
an institutional framework with the participation of local, regional, and national
and even international entities such as various relief organizations;

Strengthening
the monitoring systems for climate change and floods, while
institutionalizing the warning mechanisms;

Decentralizing
the decision-making process to the local level to ensure prompt action,
transferring financial resources and enhancing the technical expertise of
the flood mitigation team.

2.2. The Role of the Private Sector:

Depending
upon the degree of the economic activity in which the private organizations are
involved and the amount of revenue generated by these activities, the
organizations should have different incentives to engage in vulnerability
management. Their strategies must integrate the expertise developed to handle hazards
into vulnerability management and should foster productive activities as part
of the reconstruction efforts. The institutional and legal framework should
provide comprehensive regulations whereby private agents find it in their best
interest to be actively involved in the vulnerability management.

As is
evident from this chapter, it takes a perfect synchronization between the
various levels of the city’s government, the planning authorities and various
sections of the civil society as well as a proper harmonization within these
bodies to build up a sound flood mitigation mechanism for the city of Mumbai. Their
coordination is critical at various stages of the flood management process,
including the stage prior to the floods, during the floods and after their occurrence.

Adopting
this framework, essentially in that order can ensure reduction in the intensity
of the inundation that disrupts the life and working of the city of Mumbai every year during
the monsoons. Likewise it would also help conserve this water and help prevent the droughts that plague the state each year; a fact that seems like a paradox in the city that receives such a heavy downpour.

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About Me

I graduated with a Bachelor's degree in Architecture from the University of Mumbai.
I hold a Master's Degree in Urban Planning from california State University(San Jose).
I have worked as an Architect/Planner for about 11 years in India and the United States of America.